Ultra high frequency device



Sept. 24, 1946.

D. G. CLIFFORD ErAL 2,407,974

ULTRA HIGH FREQUENCY DEVICE Filled Dec. 29, 1942 ATTORNEY Patented Sept.24, 1946 UNITED STA-TES PATENT orificeI l2,407,9rc ULTRA HIGH FRQUNGYDEVICEl David Gordon Clifford, Palo Alto, Calif., and Ilia',` E;Mouromtsei,` Montclair, N; J., assignors to Westinghouse ElectricCorporation, East Pittsburgh, Pa., a corporation ofv PennsylvaniaApplication December'29, 1942-, Serial` No; 170;{190

4 Claims. (Cl. 2504215) This invention relates generally to ultra highfecti'vef and ecient ultra high frequency device characterized. as acavity resonator detector.

Likewise, from a general aspect, an object of the invention is` to"overcome the difficulties enu-` merated above` and to materially improveprior arlt constructicnsA of ultra highI frequency devlic'esandespecially diodes Y More specifically an object of the'l invention is toprovide an ultra high frequency device aschar-` acterized wherein4tuningi is obtained while the l electron emission and receptioncharacteristics a few thousandths of an inch. Thus onediih- I cultyfencountered in the prior art has been to l adequately reduce the spacingand maintain an evenV spacing of so srnall an amount without a contactinadvertently" occurring and short circuit resulting.

In considering the incorporation ofaresonant cavity as an integral partof a diode as above characterized, and wherein the electrodes of thediode'Al are reentrant intoy the resonant cavitythe problem of tuningwithout disturbing the elec'- -trode spacing has heretofore eludedradequate solution. The necessity of avoidingv contact of the electrodesreferred to above is a more serious problem when one of the electrodeshas to be moved for tuningE purposes thanwhen both are permanently*fixed. A further difticulty is ,also introduced, in that heretofore ashifting of one electrode for tuning purposes not only changed the-Lcapacitative relation of the' electrodes', but altered the electrodeyspacingA and transit time of the electrons, whichA was highlydetrimental.

When utilizing a resonant cavity for ultra high frequency oscillations,the' interior or cavity wall constitutes a conductive surface for high.frequency current. Continuity of that surface is desirable with minimumYof interruption. Inasmuch, however, as part ofthe surface is connected.with the anode and another part with the cathode, and` anode andcathodehave to be at different D; C. potentials, a discontinuity meetingthis circumstance follows of necessity. 'Ihe problem `thereforepresentsitself of providing a structure of resonator which has a'discontinuity edefctivetolmaintain difference of'D. C.' potentialwithout materially interfering with the continuity for high frequencycurrent flow.

The present invention accordingly has for its general object theprovision" of' improved, ef-

remain the same;-

Of` analogous nature isi another object which thel invention seeks toaccomplish, namely,Y that capa'citative variationrnay be accomplishedwithout disturbing the relation Ofthe@ emission effect between the diodeelectrodes:

Another object of the' invention is to obtain mechanical rigidity ofanelectrode notwithstand= ing Inova-bility thereof for tuning purposes.

A further object ofthe" invention isl to permit substantiallyunirripaired H. FL. current" flowk on the interior or cavity wallwhilemaintainig a discontinuity'in the wall for other purposes Y Stillfurther objects of the invention will appear as the? descriptionprogresses, both by di- Y rect? recitation thereof and by; implicationfrom the context.

Referring to the accompanying drawing in which like numerals,` ofreference indicate similar parts throughout the several' views;

Figure 1 is a vertical sectionalview of anultia high frequency deviceconstituted as adiode de'- tector. i

Figure-"2 across-Section on line II-TI of Fig; I. y

Figure 3'i`s` an enlargement ofithatpartof Fig. 1 showing thestructural' assembly bywhich' effectivediscontinuity i's obtained as* toD; C. potentialfbu't with theV effect of electricalic'ontinuity iiiregards to the H. E. current; and

Figure' 4 is a viewv siniila'rto' Fig.' 3 showing a modifiedconstruction. 1

In thespeciiic embodiment of the invention illustrated in said'Vdrawing, thereference'fnn'iexal lildesiglnates a sealed envelope,shownas of glass, with a reentrant glass stem Il therein' from whichprojects a metallic; collar I2 flared at itsupper'end to provide a'harige I3 in a plane transverse to the' saidv collar. Above the collarand flange isa tubular cathode I44 the upper end of which isclosed, asby integral end `I'5,.and the lower end. of' which has a. Wide ange I6priojecting radially considerably" beyond. the fiang'e |3 of' the` saidvcollar- 122` The cathode, flange` B otherwise.

rests fiatwise on the collar fiange I3, coaxial therewith and securedthereto as by Welding or Within the cathode I4 is a suitable heater IIhere illustrated as av coiled filament attached to appropriate lead-inwires I8 sealed through stem III.,

Coaxial with the cathode I4 is an anode I9' the lower part of which ishollow to provide a skirt portion 2l)` which girdles the upper endportion of the cathode in desired closely spaced relation thereto forobtaining the desired short transit time of electron path from cathodeto anode. The cathode is indicated as having an emissive oxide coating2| on the cylindrical portion thereof engirdled by the anode.4Particular attention is called to the fact that emissionrfrom thecathode ls preferably restricted to the region therefrom by mica orother dielectric 33. While the headers have peripheral cylindricalportions 3| for welding or otherwise securing the same to the outer wall23 of the resonant chamber, the part of primary importance is the Vplateor Washer-like body portion 32 of the inner header over- H. F. currentacross the area of D. C. disconincluded between the cylindrical walls ofthe` cathode and skirt portion of the anode.

The region within which cathode I4 and skirt portion of anode I9` arelocated, is constructed as a resonant chamber 22 the walls of which aremetal. The specinc construction involved provides a cylindrical outersidewall 23, preferably of copper, coaxial with the cathode and anodeand having its lower margin feather-edged and sealed to the glassportion 0f the envelopeand thereby constituting a part of the saidenvelope.

The upper vpart of said side wall 23 is provided with an inner shoulder24 for properly locating and supporting the rim or edge of a transverseflexible metallic diaphragm 25. The body portion of anode I'S'projectsthrough the middle of said diaphragm, and said diaphragm is vacuumsealed both to the anodeand to said outer wall. By virtue o1" theresilient flexibility of the diaphragm, the length of the chamber may bevaried as well as a changecbeing obtained in capacity between anode andcathode, and thereby permits desired tuning of the same. k

Both for tuning purposes and for accurate rigid mounting of the anode,the upper end of the anode is shown of sturdy construction and carriedby an equally sturdy capV ZS'in turn supported atits outer margin fromthe side wall 23 of the resonator chamber. The structure illustratedincludes a ring 2'I brazed or otherwise secured onthe exterior of saidwall 23 next the 32 is made radially a quarter wave length in dielectric30 referredV to the generated wave of oscillations in the resonantchamber. Wave length in dielectric 30 is shorter than in airor vacuum ofthe chamber. The construction accordingly sets up ahigh impedancewat theouter periphery of flange I6 which reects a low impedance at the inner`peripheral edge of plate 32 thereby presenting the eifect of electricalcontinuityV across the gap between flange and plate at the innerperiphery of the said plate.

For more denitely assuring the condition of high impedance at theperiphery of the flange, a vconstruction such as shown in Figure/1 maybe employedx In this instance the headers are constructed as before, butspaced apart somewhat Vfarther to accommodate a different flange conasbefore, a quarter wave length measured in the upper edge thereof andthreaded on its outer surface tointer-engage with threads 28 on'theinside of a .skirtV portion of said cap 26. Similarly theupper end ofanode I9 provides ay stern dielectric 35a intervening between theoverlapping portions. At the underside kof the ,ilange is an impedancesection comprised ofan open annular cavity 30h between the under side of`a part of said iange vand a parallel plate 3Go the inner periphery ofwhich is bent upwardly and secured,V

by welding or otherwise to said flange, the. upwardly bent portion 35dforming an innerend wall for the annular cavity 30h.v The outerperiphery of the parallel plate 33e turns upward beyond the end of angeIiia, as at 33e with a gap 39j between the said up-turned Vend 30e andend Vofiiange IEa. Part of dielectric 30a closes the end of gap 30j andthel parts are proportioned to establish substantially a free spacequarter wave length distance from the said closed Y end 39d to thedielectric'closure ofY gap 3f. yThe .i low impedance at closed endBildrwill, accordingly considerable rotation of the cap is required fora.v small longitudinal movement of the anode,

thereby obtaining va fine tuning adjustment.

and the Vresonator side wall. The structure shown consists in providinga pair ofheaders, one above and theother below said flange and separatedreilect a high impedance at gap 30j, as desired, and accordingly insuresa high impedance at the periphery of lflange Ilia toY insure, in turn, alow impedance at the inner periphery of plate 32. It may be furtheradded that the dielectric, k'such as mica, fills the region beyondupturned end or rim 30e and the wall 23 of-the resonant chamber, as wellas the space between thelower header and the cavity-forming under plate33o. A few holes or slots 3tlg may be provided from the evacuatedchamber into annular cavity 30h for enabling that cavity likewise to beevacuated.

In practice, the device' is evacuated through the stem, as bytubulationopening 33 therein,

therebeing suitable slots 34 in the collar I2 and slots 35 in ange I 6or I 6a to accomplish'complete cutgassing so that resonant chamber 22will function in vacuum. oscillations set up in said chamber may betransferred for useful purpose by a usualoutputmeans, suchas concentricline and loop 36 shown.

It may now be particularly pointed out that by proper choice ofdimensions of the several parts, the spacing of cathode and anode can bevery small, limited only by mechanical considerations, thus makingpossible a time of transit in this diode consistent with satisfactoryoperation at ultra high frequencies. The change in the lump-ed capacityof the device due to movement of the anode it with diaphragm 25, withcorresponding change of frequency for tuning purposes, does not afiectthe transit time of electrons between cathode and anode. Likewise thedielectric spacing of flange and plates with impedance control betweenthe cathode and outer wall provides an eiiicient means for obtaining ahigh frequency rectified current or beat frequency.

While arbitrarily selected eXemplifications of the invention have beenherein shown, it is to be understood that this has been done throughnecessity of presenting a physical embodiment of the invention and ittherefore follows that all matter contained in the specification ordepicted in the drawing shall be interpreted as illustrative and notnecessarily in a limiting sense, and as setting forth the true` scope ofinvention by statements of both the generic and specic features thereofwhich as a matter of language enceinpass the inventive concept.

We claim:

1. An ultra high frequency device comprising electrodes of which one isa cylindrical cathode and another is an anode having a cylindrical skirtportion telescopically overlapping an end of the cathode, said cathodehaving an emissive portion and a non-emissive capacitative portion incontinuation of the emissive portion and the emissive portion being atthe said end overlapped by the cylindrical skirt portion of the anode,`

said skirt portion being radially opposite the entire emissive portionof the cathode, and the non-emissive portion of the cathode projectingfrom said skirt, an enclosure around said electrodes, and movable meansextending from said enclosure to one of said electrodes for adjustingthe telescopic overlap of said electrodes longitudinally and therebyvarying the inter-electrode capacity while maintaining constantelectronpath spacing between said electrodes.

2. An ultra high frequency device comprising a diode structure having acathode and anode and evacuated enclosure therefor, said cathode andanode overlapping and having a constant radial spacing for the eiectronpath therebetween and telescopically adjustable as to distance ofoverlap for varying inter-electrode capacity thereat, and means otherthan said spacing establishing direct current discontinuity in theenclosure between the cathode and anode comprising parts insulated fromeach other and overlapping an odd quarter wave-length distance andestablishing thereat an effect of negligible impedance to high frequencycurrent and establishing eifect of electrical continuity t0 highfrequency current.

3. An ultra high frequency device comprising a metallic enclosureforming a resonator, a cathode and an anode each within said resonator,and an impedance section within said enclosure comprising partsinsulated from each other and overlapping an odd quarter wave-lengthdistance, said cathode being connected with one of said overlappingparts of the impedance section and said anode being connected withanother of said overlapping parts of the impedance section, whereby saidimpedance section establishes a direct currentA discontinuity betweenthe cathode and anode and establishes thereat an eect of negligibleimpedance to high frequency current and establishes effect of electricalcontinuity for high frequency current.

4. An ultra high frequency device comprising a metallic enclosureforming a resonator, a cathode and an anode in said resonator, saidcathode having a iange projecting laterally therefrom and said enclosurehaving a plate overlapping said fiange a distance substantially equal toa quarter wave-length in dielectric, and dielectric between saidoverlapping plate and flange.

DAVID GORDON CLIFFORD.

ILIA E. MOUROMTSEFF.

